1. Field of the Disclosure
The present invention relates to a laser pattern mask, and more particularly, to the laser pattern mask which can reduce a tack time at the time a layer is patterned by laser ablation for improving a yield; and a method for fabricating the same.
2. Discussion of the Related Art
In general, as an information oriented society is developed, demands for display devices increase gradually in various forms, and to meet this demands, different kinds of flat display devices, such as LCD (Liquid Crystal Display Device), PDP (Plasma Display Panel), ELD (Electro Luminescent Display), VFD (Vacuum Fluorescent Display) and so on, have been researched, and some of which are utilized as display devices in different equipments, currently.
In general, printing process or photolithography process is used for patterning a plurality of layers of the flat display device.
In the meantime, currently, as a trend for producing larger flat display devices is continuous, and a multiple panel cutting process has been developed, in which a plurality of substrates are formed on one mother substrate for improving productivity and saving a cost of the flat display device, the laser ablation process has been developed as a method for applying the multiple panel cutting process to the trend of producing the larger flat display devices, smoothly.
The laser ablation process enables accurate and effective exposure of a layer on the mother substrate to a laser beam for patterning the layer.
A laser ablation device will be described with reference to the attached drawings.
FIG. 1 illustrates the laser ablation device, and FIG. 2 illustrates a section of a laser pattern mask in FIG. 1.
Referring to FIG. 1, the laser ablation device is provided with a light source 10, a beam shaping unit 15, a laser pattern mask 20, a beam steering unit 25, and a projection lens 30, for applying the laser beam to the mother substrate through the following steps.
The laser beam from the light source has a cross section involved in convergence or divergence as the laser beam passes through the beam shaping unit 15, and passes through the laser pattern mask 20 for patterning.
Referring to FIG. 2, the laser pattern mask 20 (See FIG. 1) has a laser shielding pattern 130 to form opened regions to the base substrate 100.
In this instance, the opened regions are regions which allow the laser beam to pass therethrough.
The base substrate 100 is formed of quartz having good light transmissivity, and the laser shielding pattern 130 is formed of opaque metal, such as chrome Cr or chrome oxide mostly, in general.
Referring to FIG. 1 again, the laser beam is involved in a direction change as the laser beam passes through the beam steering unit 25 and has magnification thereof fixed as the laser beam passes through the projection lens 30. And, as laser beam passed through the projection lens 30 thus is incident on a layer of the mother substrate 70, the layer is patterned the same as a pattern of the laser pattern mask 20.
Since the mother substrate 70 has a plurality of panels 70a, the layer is required to be patterned into a plurality of identical patterns. In this instance, the plurality of identical patterns are patterned, not at a time, but one by one while the mother substrate 70 moves in right and left directions.
In the meantime, if the layer is patterned while the mother substrate 70 moves in right and left directions, a stitching error is liable to take place, increasing a tack time to make a yield poor.
Consequently, though a method is devised, in which an entire layer on the mother substrate 70 is patterned at a time, since laser energy the same with laser energy applied to the layer of the mother substrate 70 is applied to the laser pattern mask 20, the laser shielding pattern 130 of the laser pattern mask 20 is damaged, causing a problem in that a laser shielding capability of the laser shielding pattern 130 becomes poor.